Silane plasma

The deposition of amoriDhous hydrogenated silicon (a-Si H) from a silane plasma doped witli diborane (B2 Hg) or phosphine (PH ) to produce p-type or n-type silicon is important in tlie semiconductor industry. The plasma process produces films witli a much lower defect density in comparison witli deposition by sputtering or evaporation. 

The SiH radical is tlie dominant growtli precursor for tlie fonnation of tlie a-Si H films in a low-temperature silane plasma [32]. Silane molecules are dissociated by energetic plasma electrons ... 

Admixtures of oxygen or oxidizing agents such as N2O to the silane plasma enable the deposition of Si02 films. Other Si-containing compounds such as SiCl or tetraethoxysilane (Si(OCH2CH2)4) are used for plasma-enlranced Si02 deposition at lower temperatures [33],... 

Table 1. Electron Impact Dissociative Processes Operative in Silane Plasma ...

In order to relate material properties with plasma properties, several plasma diagnostic techniques are used. The main techniques for the characterization of silane-hydrogen deposition plasmas are optical spectroscopy, electrostatic probes, mass spectrometry, and ellipsometry [117, 286]. Optical emission spectroscopy (OES) is a noninvasive technique and has been developed for identification of Si, SiH, Si+, and species in the plasma. Active spectroscopy, such as laser induced fluorescence (LIF), also allows for the detection of radicals in the plasma. Mass spectrometry enables the study of ion and radical chemistry in the discharge, either ex situ or in situ. The Langmuir probe technique is simple and very suitable for measuring plasma characteristics in nonreactive plasmas. In case of silane plasma it can be used, but it is difficult. Ellipsometry is used to follow the deposition process in situ. 

The plasma potential is about 25 V (Figure 63a). This value of the plasma potential is typical for the silane plasmas in the asymmetric capacitively coupled RF reactors as used in the ASTER deposition system, and is also commonly found in argon or hydrogen plasmas [170, 280, 327]. From the considerable decrease of the dc self-bias with increasing frequency (Figure 63a) it is inferred that the... 

In contrast, Heintze and Zedlitz [236] also presented data on the plasma potential as function of frequency in silane plasmas the plasma potential varies from about 27 V at 35 MHz to about 20 V at 180 MHz. Moreover, Dutta et al. [284] used a symmetric capacitively coupled RF reactor and estimated the plasma potential in their system from the applied voltage at the powered electrode. A decrease of the plasma potential from 45 V at 13.56 MHz to only 15 V at 70 MHz is observed. This difference in behavior is thought to be solely due to the different reactor geometries. 

X-ray photoelectron spectroscopy (XPS) was used for elemental analysis of plasma-deposited polymer films. The photoelectron spectrometer (Physical Electronics, Model 548) was used with an X-ray source of Mg Ka (1253.6 eV). Fourier transform infrared (FTIR) spectra of plasma polymers deposited on the steel substrate were recorded on a Perkin-Elmer Model 1750 spectrophotometer using the attenuated total reflection (ATR) technique. The silane plasma-deposited steel sample was cut to match precisely the surface of the reflection element, which was a high refractive index KRS-5 crystal. 

Cold-rolled steel panels were purchased from Advanced Coating Technologies, Inc. (Hillsdale, Michigan). Silane chemicals (methylsilane, trimethylsilane, and tetramethylsilane) were purchased from Petrarch Systems, Inc. The silane plasma-deposited steel was then dip-coated with a polymer film 10-25 pim thick. The polymer coating resins used were silane-modified polymers with functionalities such as hydroxyl, acrylate, or amine. 

The bonding environments surroundir alkyl. Si—CH3, Si—CH2, Si—H, and Si ing is believed to be a typical oxane I sitions of deposited silane plasma pob C/Si and O/ Si atomic ratios increas Organofunctional silane polymer coati silane polymers. Corrosion performar to be excellent. The results were partic silane polymer and organofunctiona phosphated steel substrates. 

So-called clustering reactions of SiH + ions (n = 0-3) with silanes and other small molecules have attracted considerable interest. In particular, the reaction sequences which might lead to the formation of large-sized clusters have received attention, as these processes are thought to be involved in undesirable dust-formation which occurs during silicon-film depositions from silane plasmas and vapors97-99. Thus, Mandich and Reents... 

In Volume 21, Part A, the preparation of a-Si H by rf and dc glow discharges, sputtering, ion-cluster beam, CVD, and homo-CVD techniques is discussed along with the characteristics of the silane plasma and the resultant atomic and electronic structure and characteristics. 

A. Yuuki, Y. Matsui, K. Tachibana A study on radical fluxes in silane plasma CVD from trench coverage analysis. Jpn. J. Appl. Phys. 28, 212 (1989)... 

Much of the direct experimental information about the radicals and ions in the silane plasma comes from mass spectrometry. Fig. 2.9 ows the concentrations as a function of argon dilution for a typical low power plasma. Gallagher and Scott (1987) find that SiHj accounts for at least 80 % of the gas radicals in a pure silane plasma. Argon dilution increases the concentration of other radicals and these eventually dominate the plasma. 

Furthermore, the broad TMS signal is similar to the reported silicon-dangling bond centers observed from silane plasma deposition [13,14]. In addition, a well-studied class of paramagnetic silicon defects, the Pb centers [15,16], has precisely the g anisotropy (fig 0.006) required to account for the width of the TMS signal. The overall effect of including all these Pb defects together would be to... 

Oldfield, F.F. Cowan, D.L. Yasuda, H.K. ESR study of trimethyl silane plasma polymer. Part II Effect of consecutive treatments and mixed gases. Plasmas Polym. 2001, 6, 51-69. 

Stamou, S. Mataras, D. Rapakoulias, D. Spatial rotational temperature and emission intensity in silane plasma. J. Phy. D Appl. Phy. 1998, 31, 2513-2520. 

Kessels, W. M. M., van de Sanden, M. C. M., and Schram, D. C., Hydrogen-poor cationic silicon clusters in an expanding argon-hydrogen-silane plasma. Appl Phys Lett. 72, 2397-2399 (1998). 

---